Use of unmanned aerial vehicles (UAVs) has become increasingly common with the advent of automated flight based on GPS as well as real-time communications that allow for remote UAV operation. For example, UAVs are commonly used by the military to provide surveillance, reconnaissance, target acquisition, communications relay, casualty evacuation, ordinance delivery and/or supply flights.
There are various types of UAV configurations. Generally, such UAV configurations may be separated into three categories. A first UAV configuration is a fixed wing configuration that is similar to an airplane. A second configuration is a helicopter type configuration that utilizes a rotor mounted above the vehicle to provide lift and thrust. A third configuration is a ducted type configuration having a fuselage with a ducted rotor that provides vertical takeoff and landing capabilities. Each of these UAV configurations provides certain benefits and drawbacks.
For instance, fixed wing UAVs typically take off and land like an ordinary airplane. Accordingly, the UAV requires a runway to create sufficient airflow over the wings of the UAV such that it may take off. Likewise, landing may require a runway. A further difficulty with fixed wing UAV configurations is that such UAVs may not operate effectively in confined air space. That is, as fixed wing UAVs require forward motion to maintain lift, they are not capable of hovering over a fixed spatial point. Accordingly, such fixed wing UAVs are not optimized at delivering logistics supplies, ordinances or payloads to designated targets. However, fixed wing UAVs do provide the benefit of being able to travel at greater speeds and longer distances than most other UAV configurations as they have better aerodynamic lift and drag characteristics.
Helicopter UAV configurations provide the benefit of vertical takeoff and landing as well as the ability to hover over fixed spatial points. This allows helicopter UAV configurations to be utilized to deliver ordinances and/or supplies to designated locations. However, such helicopter UAV configurations often have relatively slow forward speeds as the rotating blades create a large aerodynamic drag. In this regard, both the speed and the range of helicopter UAV configurations can be limited.
Ducted type UAVs often include a ducted fuselage shrouding coaxial, counter-rotating rotors. Such rotors are designed to provide thrust necessary for both vertical and forward flights. In this regard, such ducted type UAVs also permit vertical takeoff and landing. Typically, to provide forward movement (e.g., horizontal movement), the aircraft fuselage must nose down in order to generate horizontal thrust. Such ducted type UAVs often suffer from stability issues as well as limited speed in forward flight. In particular, the ducted rotors cannot be oriented such that the plane of rotors is perpendicular to the direction of travel of the aircraft.